Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<algorithm>
#include<iostream>
#include<vector>
#include<queue>
using namespace std;
typedef long long lint;
typedef vector<int>vi;
typedef pair<int,int>pii;
#define rep(i,n)for(int i=0;i<(int)(n);++i)

string s[50];
int d[50][50];

int main(){
  int h,w;
  cin>>h>>w;
  rep(i,h)
    cin>>s[i];
  rep(i,h)rep(j,w)d[i][j]=-1;
  queue<pii>q;
  q.push(pii(0,0));
  d[0][0]=0;
  int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};
  while(!q.empty()){
    pii t=q.front();q.pop();
    int x=t.first,y=t.second;
    if(s[x][y]=='#')continue;
    rep(dir,4){
      int nx=x+dx[dir],ny=y+dy[dir];
      if(nx<0||nx>=h||ny<0||ny>=w)continue;
      if(d[nx][ny]>=0)continue;
      d[nx][ny]=d[x][y]+1;
      q.push(pii(nx,ny));
    }
  }
  int black=0;
  rep(i,h)rep(j,w)if(s[i][j]=='#')black++;
  if(d[h-1][w-1]==-1)cout<<-1<<endl;
  else cout<<h*w-d[h-1][w-1]-1-black<<endl;
}